I'm not sure why everybody automatically assumes the Nats won't sign any free agents. It wouldn't of made sense to sign any big free agents the last few years. The time may not even be this off-season. But I would expect them to supplement whatever needs they need after getting an idea who from the minors is going to pan out and who's not. In todays Post Rizzo mentions getting the next championship team from the minors, free agency and trades. They signed who they needed to in the past when it was appropriate and until they don't I wouldn't assume they won't.
BTW, unlike the O's owner who has come out and says he's not signing free agents.